In a cold cathode lamp (e.g., a cold cathode fluorescent lamp (CCFL)) used in a scanner, mercury atoms are excited to radiate out ultraviolet (UV) lights, which then let fluorescent material emit out visible lights.
As shown in FIG. 2, a cold cathode lamp 60 is formed by coating fluorescent lacquer on part of the inward wall of a lamp 61 made of quartz. Reflecting coating layers 62 and 63 are then deposited or added on the lamp 61 to let the cold cathode lamp have a directionality. All light emitted by the cold cathode lamp 60 will be radiated out via a radiation aperture provided by the reflecting coating layers 62 and 63.
As shown in FIG. 1, when the cold cathode lamp 60 is assembled in a scanner 50, a plurality of tabular or tubular pre-heaters 70 are provided near the cold cathode lamp 60 to heat the cold cathode lamp 60 in advance. Or the pre-heaters 70 are provided near the surface of the opposed side of the document-read position.
In this way, however, the assembly cost of the cold cathode lamp 60 and the pre-heaters 70 will be increased.
Moreover, because the cold cathode lamp 60 is unstable at low temperatures, the brightness thereof will be unstable until a certain time elapses.
Furthermore, the pre-heaters 70 and the cold cathode lamp 60 are powered by the same power source after the scanner 50 is activated, hence dissipating more power.
Accordingly, the present invention aims to provide a warmth-keeping structure of cold cathode lamp to resolve the problems in the prior art.